The present invention relates to an electrical interface and, more particularly, to an electrical interface that permits a machine, having a manually actuated joystick control, to be retrofitted for automatic control.
Various types of machines, such as earth moving equipment, are commonly manufactured and sold with controls, such as joystick controls, that provide for manual control of some machine functions. Some machines may also include a provision for automatic control of various machine functions. For example, the position of a machine or an element of the machine, such as a cutting blade or bucket, may be automatically controlled by reference to a positional reference such as the output of a global positioning system (GPS) receiver, or a laser receiver that detects reference beams of laser light. However, many machines are sold without a provision for automatic control, and it is common for the owner of such a machine to retrofit it so that it can be controlled automatically. Machines of this type typically have hydraulic cylinders that move or reorient the various machine elements, either directly or through mechanical linkages. The application of hydraulic fluid to these cylinders is controlled by valves that are typically electrically actuated. The electrical control signals that control valve actuation are provided by a machine control, which includes appropriate circuitry and microprocessors, and operates under the control of one or more joystick devices.
In the past, when a manually controlled machine was retrofitted for automatic control, the automatic control system was usually added to the machine control system by tapping into the hydraulic lines that supply hydraulic fluid to the cylinders. The hydraulic lines are typically reworked for this purpose so that hydraulic fluid can be supplied to the cylinders from either the manual control system or the automatic control system. While the resulting modified hydraulic system typically functions well, the retrofitting process is time consuming, and cumbersome. It is seen, therefore, that there is a need for a control arrangement for retrofitting a machine of this type in which the retrofitting process is facilitated, and the time and effort required for retrofitting are reduced.